As magnetic recording is pushed to higher areal densities, perpendicular media may offer the advantage of thermal stability over longitudinal media. Despite the rapid progress of perpendicular recording technology in recent years, there remain a few technical challenges. One of these is the non-zero remanence state that is associated with a single pole writer after the write current has been terminated, often referred as self-pole-erasure (SPE).
The physical origin of SPE is the strong ferromagnetic exchange coupling of pole tip while in its remanent state, which aligns the magnetization vertically and causes the erasure of data on disk. SPE will be aggravated when the perpendicular media are DC magnetized and the magnetic field generated from said perpendicular media causes the vertical remanent state to be energy-favorable.
This invention improves pole erasure performance associated with a PMR writer. It provides an alternative solution to the pole erasure problem by changing only the geometry/structure of the main pole, without changing pole materials. The process is compatible with current practice. When combined with future material improvements, even greater reductions of pole erasure can be expected.
A routine search of the prior art was performed with the following references of interest being found: In U.S. Pat. No. 6,721,131 and in U.S. Patent Application 2002/0131203, Litvinov et al disclose a decoupling layer between high and low magnetic moment portions of a write pole to minimize magnetic remanence. In order to minimize changes to the process for manufacturing their write head they place this decoupling layer in a plane normal to the ABS (air bearing surface), thereby surrendering the possibility of shaping the pole piece so as to concentrate the write flux in the pole tip. The present invention teaches a structure and process whereby the decoupling layer is placed in a plane that is parallel to the ABS.